Let ϕ be the phase angle between the line current and line voltage, and α be the load angle. The per phase mechanical power developed by a synchronous motor is:

• A. \(\frac{{{E_b}V}}{{{X_S}}}\sin \phi \)
• B. \(\frac{{{E_b}V}}{{{X_S}}}\cos \alpha \)
• C. \(\frac{{{E_b}V}}{{{X_s}}}\cos \phi \)
• D. \(\frac{{{E_b}V}}{{{X_S}}}\sin \alpha \)